1. Field of the Invention
The present invention relates to decoys and targets of microwave radar systems and more particularly to microwave radar systems which utilize the principles of Doppler shift for moving target indication and/or velocity calculation, etc.
2. Description of the Prior Art
Much of the prior art in the field of electronic counter-measures for radar systems is has a secrecy restriction within the U.S. Patent Office. The inventor has searched the files of the U.S. Patent Office for the best available prior art.
In his article, entitled Targets for Microwave Radar Navigation, Sloan D. Robertson wrote about the effective echoing areas of certain radar targets and how these areas could be calculated. He published his article in the Bell System Technical Journal, Volume 28, Issue 4, October, 1947, on pages 852 through 869.
U.S. Pat. No. 3,010,103, entitled Radar Reflective Tow Target, issued to Robert J. Hopper and Orson B. Lolmaugh on Nov. 21, 1961, teaches an aerial tow target for training pilots in the use of equipment for detecting and tracking aerial targets and the use of various automatic equipment for such purposes as fire control, missile launching control and target interception. These two targets were relatively inexpensive in comparison to the cost of drone airplanes. The two targets used a plurality of corner reflectors for reflecting the radar beams.
In his article entitled Radar Targets: How Objects Look to Radio-Wave Eyes, M. W. Hosking wrote about the purpose of a radar system which is to obtain information about its target and in many cases to try and differentiate between, or identify, several objects which may have reflected the system's questing beam. He published his article in Wireless World in March, 1976 on pages 44 through 47.
U.S. Pat. No. 2,823,376, entitled Stringer Radar Reflective Tow Targer, issued to Robert P. Baldwin and Raymond H. Eckert on Feb. 11, 1958, teaches a method of making an improved tow target which is not only more stable in flight in relation to its light weight, but has a mechanism which controls the magnitude and dispersal of radar beams reflected from the tow target. The improved tow target includes a plurality of reflecting surfaces, which are disposed along its longitudinal axis, and rotates about its longitudinal axis, in order to disperse the reflected energy.
U.S. Pat. No. 3,016,532, entitled Tow Target, issued to Bruce E. Del Mar on Jan. 9, 1962, teaches an aerial target to be towed by aircraft for military training purposes as well as for carrying out various tests and experiments. The tow target includes a plurality of corner reflectors which are circumferentially arranged and a mechanism for rotating the plurality of corner reflectors. The object of this rotation is to cause the intensity of the overall radar reflection to pulsate at a frequency which is equal to the revolutions per minute of the rotating corner reflectors.
U.S. Pat. No. 3,010,103 also teaches that the dimension of its larger reflector should be at least 61/2 times the wave length of the radar signals in order to effect mono-static reflection. In view of the size constraints of decoys and tow targets it would be beneficial to reduce the size of the reflectors.
U.S. Pat. No. 4,101,736, entitled Device for Increasing the Compliance of a Speaker Enclosure, issued to Eugene J. Czerwinski on July 18, 1978, teaches the use of a gas having a gamma less than 1.4 and the product of its density and the square of the speed of sound therein less than the same product for air in a soft, pliable bag thereby increasing the acoustical size of the speaker without increasing the physical size of the speaker.
The inventor realizes that there may be patents describing systems for decoys which are maintained within the secret and restricted status. The inventor also realizes that an apparatus which defeats radar systems by misleading them about a radar target's present speed may also be restricted by a secrecy order. Nonetheless the inventor envisions many practical uses of his apparatus.